The problem of stabilizing vessels at sea (or in larger inland bodies of water) particularly for the purpose of increasing the comfort of passengers has been investigated for many years. Most of these investigations, and the apparatus resulting therefrom, were attempts to reduce the vessel's roll. Roll motion is generally considered to be the easiest to control without affecting the overall hydro-dynamic performance of the vessel and tends to have the maximum undesirable effects on individuals being carried on the vessel. Most of these prior inquiries dealt with the problem of roll stability of vessels underway. Such things as hydraulic stabilizers that move water from one side of the vessel to the other to counteract the vessels tendency to roll under the inducement of swells have been developed and put into use. Also hydro-dynamic fins have been utilized that use the force of the vessel underway to produce an upward or downward lift opposite the direction of the roll tendency.
Relatively little attention has been directed to the problem of vessel roll while the vessel is at rest. In certain marine operations, for example in still fishing, where the vessel is at rest (at anchor or drifting with the surface currents) the tendency of the ocean swells to produce rolling is of sufficient magnitude that many persons experience motion discomfort. In addition, such rolling motion is objectionable for crewmembers who are attempting to carry out operations on such vessels, such as the placement of fishing poles, and such motion inhibits free movement about the vessel. The problem is particularly acute in many personal fishing vessels which vessels have a relatively narrow beam and therefore are subject to larger induced roll magnitudes.
Float type stabilizers that are on outriggers have a limited tendency to reduce the roll of a vessel but only to the extent that they would tend to reduce overroling; that is the tendency of a vessel to roll beyond the inclination of the water surface itself. However, since such devices are rigidly interconnected with the vessel they cannot prevent the inclination of the vessel as a swell approaches and passes. They require an excessively large float area to achieve a significant stabilization effect. Such devices cannot easily be retracted when the vessel is underway. Various fins, skegs and other protrusions from the underside of the vessel's hull have been incorporated in an attempt to increase roll resistance. However, such devices cannot overcome rolling due to harmonic effects (the tendency of certain swell frequencies to produce a disproportionate effect) because they move in sychronization with the vessel itself. Further, such surfaces must be excessively large (due to their short lever arm) to accomplish any substantial stabilizing effect.
Accordingly it is desirable to have a roll stabilizer for vessels at rest which is relatively small in size and uncomplicated in operation and which substantially reduces the roll magnitude of swell induced rolling. Such a device is especially desirable where it is self adjusting and easily retractable for operations underway.